We are attempting to understand the intracellular pathways which regulate the growth and migration of vascular smooth muscle cells (smc). This is of particular interest since smooth muscle cell proliferation and migration is thought to be largely responsible to restenosis following balloon angioplasty, as well as being an initial event in atherosclerosis. Using techniques of molecular and cell biology, we are attempting to understand how extracellular (outside) signals are converted into pathways inside the cell that stimulate proliferation and movement. We have recently demonstrated that smc which are stimulated to grow produce large intracellular quantities of hydrogen peroxide (H2O2). This production of hydrogen peroxide has been shown to be necessary for smcs to respond to growth factors. These results may be relevant to explaining a mechanism for the cardioprotective effects of dietary antioxidant.